Telephone system.



E. B. CORW-IN.

TELEPHONE SYSTEM. APPLICATION FILED JANJB, 1e09 RENEWED MAY 1, 1911.

1,040,633. Patented 0015.8,1912.

Zl/zfizessw: 1727677207." Q VMKSM M 16772209? 60770272 phone lies each extending to multipled.

:ing the bell and condenser in bridge of the; line, and, when free of the receiver, includ-. ing said receiver and transmitter in series thefiinpedance coil 7 in shunt of the receiver.

battery 11- and the connection of said limbl 'contact thimbles of the jacks associated with UNITED STATESPATENI OFFICE.

E'LMER R. conwm, or CHICAGO, ILLINOIS; 135mm 'ro coaw rn rnnnrnonn MANU- FAQTURING COMPANY, 0F CHICAGO,

IZFLINOIS, A'CORPORATION OF ILLINOIS.

'rELEPHoriE SYSTEM.

T a all whom it may concern: f Be.itknown that I, ELMER R. Conwrrnl citizen of the United States, residing at; Chicago, in the county of Cook and State; of Illinois, have invented a certain new and useful Improvement in Telephone S'ystems, of which the folloiving is a full, clear, con-,' cise, and exact description, reference being had to the accompanying drawings, forming? apart of this specification.

My invention relates .to telephone exchange systems, and has a number of ob-j jects and advantages which will appear by[ reference to a description of the preferredi embodiment thereof, shown in the acc0mpanying drawing, that illustrates two telejack switches at an exchange. Each tele-; phone line includes two limbs 1, 2 that ex-' tend from sub-stations to an exchange, the; lines being shown as terminating in' jack, switches 3, 3 at the exchange. The apparatus illustrated at each sub-station includes a telephone switch-hook 4, a telephone re-.; ceiver 5, a'transmitter 6, an impedance coil, 7, a call bell 8,and a condenser 9, the switch-, hook, when supporting the receiver, includwith the telephone line and each other and;

I do not limit myself to the particular. style of sub-station employed, as other outfits may be used without departing from the spirit of my invention." J

The limb 1 of each line includes an im-l edance coil 10 at the exchange, which is! nterposed between one pole of the common;

withtbe jack switch terminals. Both limbsi ofeach telephone line terminate in jack; switch contacts of the multiple jacks. A,- third jack contact is provided for each jack; switch for testing purposes, this jack contact} being in the form of a test thimble 3, the;

each line bein commonly connected with one terminal 0 a cut-off relay 12, the other, terminal of which is connected with that pole of the batter 11 which is com anion; to the battery p0 e that is connecte with the line 1. A line signal 13 is in serial relation with the limb 20f each telephone Specification oi. Letters Patent. Application flled' -J'anuary 18, 1909, Serial No. 472,860. Renewed May 4, 1911. Se

line, the battery .11 and the armature switch of the cut-off relay 12, the signal.1-3"-being located between the battery 11 and the connection ofthe corresponding limb 2 with the jack switches.

When .a subscriber initiates a call, he closes circuit of the battery 11 through the line signal 13, the unattracted armature switch of the cut-off relay 12, his switchhook, the receiver 5 and the transmitter 6 and the impedance coil 7, together with the limbs 1, 2 of his line, whereby circuit is established through the line signal 13, which is preferably a small incandescent lamp, for the purpose "f energizing the same to notify the operator that a connection is desired. The apparatus which the operator employs for answering a calling subscriber and connecting him with a called subscriber, includes the cord circuit having an answering plug 14 provided with three contacts, a tip Y contact, a sleeve contact, and a thimble contact, and a connecting plug 15 provided with contacts similar to the contacts of the answering plug 14, the tips of the plugs 14, 15 being adapted to be united for the purpose of passing telephoniccur'rents, while the sleeves of said plugs 14, 15 are similarly united, the heel contacts of said plugs, how'- ever, being adapted for inclusion iIi loca 'l s5 circuits that are rendered independent of each other by means of the condensers 16 and 17 in the talking strands, thetip and sleeve strands, of the cord circuit. Arelay 18 is connected with that portion ofthe'tip strand intervening between the condenser 16 5 and the tip of the answerin plug, this relay 18 being connected with t e upper terminal of the battery 11 and having an armature switch which isadapted positively to open 96 or positively to close one gap in the circu1tof the self-restoring clearing-out indicator 19, there being preferably but one clearingout indicator in the system of my present invention, the clearing-out indicator being 100 desirably in the form of a smal ll'ncandes--- cent lamp. When an operator has inserted the answering lug 14 intothe jaclgof a calling line, a circuit is at once established for the relay 18, which maybe traced from the u per terminal of the batteny 11, throug the winding of the relay 1 8, the tip contact of the answering plug, the t1 contact of the answering jack into Wl'llC said plug is inserted, the switch-hook, re-

ceiver, transmitter, and impedance coil at the calling subscribers station, back to the lower terminal of the battery 11, whereby the clearing-out signal 19 is not operated when the calling subscriber is responded to by the operator. The operators telephone outfit 20 is thrown at once into connect-ion with the calling line, by reason of the armature switch 21 of the relay 22, when unattracted, said armature switch 21 having two contacts connected one with the tip and the other with the sleeve strand of the cord circuit, and, when unattracted, engaging two contacts which constitute the terminals of the operators telephone set.

It will be observed that there is but one pole of the battery 11 connected with a talking strand of the cord circuit, the other pole of the battery being directly connected with a limb of each of the lines, so that the battery is fed to the linesnot by way of both strands of the cord circuit, but by way of one of the strands of the cord circuit to one limb of the line and directly to the other limb of the line, this arrangement being provided inasmuch as I have caused the receivers of the operators telephone sets normally to be connected in bridge of the cord circuits. It will be observed that inasmuch as the battery is not connected with both sides of the cord circuits, but is connected in the manner'specified, cross talk is impossible even though the operators telephone outfit is normally connected with the cords.

Having ascertained the wants of the calling subscriber, by reason of the described association of the operators telephone set with the calling telephone line, the operator tests the jack switch of the called line by holding the tip of the connecting plug 15 against the test thimble of the jack of the called line appearing before her, an audible test following if the called line is busy and no manifestation occurring if the called line is idle. The circuit that is established when the called line is busy may be traced from the upper terminal of the battery 11, through the winding of the test relay 23, the induction coil winding 24 that is in inductive relation with the induction coil of the operators telephone outfit, the normal contact of the armature switch 25, the normal contact of the armature switch 26, the tip contact of the testing plug, the thimble of the jack that is being tested, thence to the thimble of the jack into which a plug is inserted at another section of the multiple board, the thimble contact of the plug inserted into such jack at such other section of the multiple board, and either through the line of the called party, back to the other terminal of the battery 11, if the called party then happens to have his telephone off of its hook, or back to said remaining terminal of the battery 11 by way of the contact switch 27 and its normal contact and the winding of the relay 22, if the subscriber of the busy called line has not yet removed his telephone from its hook. The circuit of the test magnet 23 includes its own armature and contact, the armature of said magnet 23 thus vibrating when the tip of a testing plug, in finding a busy line, establishes circuit through said test magnet, whereby the coil 24 of the induction coil is intermittently included in circuit, thereby to convey to the operator. a characteristic signal which informs her that the called line is busy. If the called line is idle, there is no path-way to the lower terminal of battery 11, which includes the test magnet 23, and therefore no sound is occasioned in the operators receiver as a consequence of the test. If the line tested has been found idle, the connecting plug 15 is inserted in the jack of the called line, whereupon the magnet or relay 22 is energized, causing an attraction of the armature switch 21 to remove the operators telephone outfit from-circuit, the'last function of this outfit having been served when the test had been concluded. The circuit that is established for the purpose of energizing the relay 22 may be traced from the lower pole of the battery 11, I

through the winding of said relay, the armature switch 27, its normal contact, the thimble contact of the connecting plug 15, the thimble of the engaged jack of the called line to the upper terminal of the battery 11,

the circuit thus traced including the cut-off relay 12 so as to cause its energization and thereby to prevent the line signaling lamp 13 corresponding to the called line, and which may be located at another section of the board, from glowing when the called subscriber responds to the signal that is occasioned at his station automatically, as will now be described. The right-hand armature switch 25 of the magnet 22 is attracted when the armature switch 21 is attracted, thereby first to exclude the test magnet 23 and test coil 24 from circuit, the alternate contact of the armature switch 25 then being engaged to connect the calling generator 26 with the line, so as to enable the transmission of current from said generator to the signal bell 8 of the called line. The circuit of the generator 26 may be traced from the ground shown below the battery 11, through the generator, the alternate contact of the armature switch 25, the normal contact of the armature switch 26, the tip contact of the connecting plug 15, the tip line spring of the jack engaged by said plug tip, the bell 8, the condenser 9, to the grounded impedance 10.

A constantly rotating two-part drum 29 has borne upon it two brushes 30 that are 1n the calling generator circuit, one of the parts of the drum 29 being in the form of a semicylindrical drum, the drum thus bein a ed intermittently to open and close t e generator circuit, so that the bell 8 is caused the battery .11, the other terminal ofthe cylindrical contact segment, while the other part of said drum is m the form-of a semi-v c lindrical segment of insulatin g material,

ta two segments together constituting intermittently to ring. When the called subscriber responds to the si a1 thus conveyed, he removes his telep one from its switch-hook, and thereby substitutes for the condenser 9 a continuous path section for current from the battery 11, for the purpose of energizing the rela winding 31 to occasion the exclusion of t e generator 26 from circuit with the called line'in the manner to be described. In order to keep the battery 11 and the generator 26 in separated relation, while affording means for permittin the batte 11 to be included in circuit wit the winding 31, I employ brushes 32 thatrest upon a drum 33 that is similar in construction to the drum 29and which is driven at the same rate of speed, the brushes restin upon each drum being in contact with t e metallic segment. thereoffwhile the brushes of the other drum are upon the insulating segment thereof. When the brushes 32 rest upon the metal segment of the drum 33,. the called subscriber having responded by removing his receiver from its switchhook, circuit m be traced from the upper terminal of the l iattery 11, the brushes 32, the winding 31, thenormal contact of the armature switch 26, the tip of the connecting plu ,the corresponding terminal of the engage attraction of the various armature switches 28, 34 and 35, the switches 28 and 34 en' ging alternate contacts in order to comp ete thetip and sleeve strands of the cord. circuit.

magnet 36 which controls the armature switches 26, 27 with the upper terminal of winding 36being connected with the other terminal of the battery 11 by way of a portion of the sleeve strand of th'e'cord circuit,

the sleeve contact of the connecting plug, the

contact of the engaged jack no, and the impedance coil 10 of the called line. Circuit having thus been; established through the magnet 36, its arma:

corresponding of the called i ture switches 26, 27 are attracted, whereby circuit conditions are brought about now to be described. The coil 31 has its circuit opened at the switch 26, but the coil 37 upon;

the same core with the coil 31has its circuit closed by a contact of armature. switch 34,

so that the armature switches 28, 34 and 35 are still attracted. The energizing circuit for the magnet 22 and cut-off relay 12 which the apt jack, the called telephone line, to the lower terminal of the battery 11. The windin 31 being thus energized, causes the 40 i mal contact of the armature switch 27, but

circuit for the magnet 22 is immediatel reestablished at the alternate contact 0 the armature switch 27, which new circuit may be traced from the lowermost pole of the battery 11, the winding of the magnet 22, the armature switch 27, its alternate contact, to the upper pole of the battery 11. The magnet 22'is thus maintained in closed circuit, to continue the exclusion of the operators telephone from circuit relation with the cord. A new circuit is established for the cut-ofi' relay 12 of the called line, to prevent theo eration of the line signal 13 of such line, w ich new circuit may be traced from the upper through the windlng of saidcutoff relay, vthe thimble of the ack engaging the connecting plug 15, the thimble contact of the connecting plug 15, acontact of the armature switch 34 directly connected with said thimble contact of the plug 15, the armature switch 34, the tip of the connecting plug engaging the 'ack switch of the called line, an the call line, to the remaining terminal of the battery 11. l't'will be seen that the circuit of the cut-oil? relay 12 of the called line has now been placed within the control of the called subscriber.

' When circuit has been established throu h the ma et 36, a lockin circuit is esta lished t enefor, which inc udes the alternate contact of the armature switch 26, and which may be traced from the upper terminal of the battery 11, said alternate contact of said armature switch 26, the winding of the magnet 36, the sleeve contact of theconncting plug, the sleeve contact of the jack engaging said plu the impedance coil 10 of the called line, to e remaining pole of the battery 11. The windin 36 is thus included in a local circuit whic is within the control of the operator exclusively. The coil 37 is included in a circuit that is governed'by the called subscriber,'and inasmuch as the position of the armature switch 34 (to ther with its companion switches 28 an 35) depends upon the -detnergization or non-energization' o the coil 37 ,the circuit of the called'subscribers rela called subscri er.

If the called subscriber should desire to become a calling subscriber, and'to that end is dependent upon the wishes to get into communicationwith his own operator,.such called subscriber will first restore his telephone receiver to its switchho'ok, thereby opening the circuit of the winding 37, thereby to open circuit of the cut-off relay 12. When the circuit of the winding 37 is once 0 ened, it cannot again be closed except n t e manner prev ously specified, the called subscriber being powerless to close a circuit through the winding 37 after he has once opened said circuit.

ole of the battery 11,

The cutofi relay 12'of the called subscriber,

therefore, when once included in open cirexcept by the operator who responds to the line signal of the called subscriber when he has removed his telephone receiver from itsswitch-hook afterhaving thrown the windings 12 and 37 out of circuit, as has been described, or by some other operator establishing connection with the called line. Thus the called subscriber renders himself independent of the connectionthat had'existed between him and the calling subscriber, and renders himself independent of the calling subscribers apparatus, for the "purpose of gaining control of his own line signal.

In accordance with my invention, the called subscriber is enabled to dissociate his line equipment from the operators equipment, 1t being my purpose to cause the calling subscriber to convey the clearing-out signal, which he does when he restores his telephone to its switch-hook. When the calling subscriber restores his receiver upon his switch-hook, the circuit of relay 18 is opened, permitting its armature to fall back and release circuit through the clearing-out signal 19. The circuit for the clearingout signal 19 may be traced from the lower 'terminal of the batteryll, the lamp 19, the armature switch of relay 18 and its normal contact, the thimble contact of the answering plug 14, the thimble contact of the engaged jack, the cut-off relay 12 of the calling line, to the upper terminal of the battery 11. It is thus an important feature of my invention to provide a system wherein the called subscriber may by his own action, without the aid of the calling subscriber, place himself in communication with his own'operator, and whereby the calling subscriber is bound to the association of his line with the connecting apparatus, inorder that such calling subscriber may convey the clearing-out signal, the calling subscribers line signal being-still dissociated from his line, so that if the calling subscriber should again take ofi' his receiver from its switch-hook during the connection of a line with the connecting apparatus, the line signal will not be operated, the clearing-out signal thus being operated by vibration of the calling subscribers switch-hook, to indicate to the operator that her attention is again required by the calling subscriber. A great advantage is afforded by this arrangement, inasmuch as the operator is enabled to notice the disconnect signal much quicker than she would a line signal, and if the calling subscriber should desire connection 'with another line,

' such new connection is expedited, as the answering plug is already in connection with the line of the calling subscriber.

It will be observed that when the answering plug is in position, the ,cut-ofi relay 12. and the relay 18 in parallel relation and in series relation with the battery 11, ter-' minals of the relays 12 and 18 being connected with'the upperterminal of the battery 11. The joint impedance of the relays 12 and 18 is caused to equal the'impedance "of the associate impedance coil- 10. By this arrangement the battery-11 is included in bridge of the calling telephone line, there being included in this bridge on one side of the battery 11, the impedance coil 10, and in this bridge on the other side of said battery 11, the joint impedance furnished by the relays 12 and 18. The batter 11 is also included in bridge of the calle telephone line, the impedance 10 of the called line being included in this bridge upon one side of the battery 11 while the same bridge contains,

upon the other side of the battery 11, the

joint impedance furnished by the relay winding 37' and the cut-off relay'12 of the called line, these latter elements being also in multiple relation. 1

ll will now describe another feature of my invention, adescription of which was omitted hitherto for the sake of clearness in the description of remaining features of my system. In accordance with the present'feature of my invention, at least one gap in the cord circuit controlled by the relay windings 31, 37 (preferably the gap controlled by the armature switch 28) is bridged by a path 38 which serves as a conductor of limited capacity for the signaling current (and which conductor may for the purpose, include high impedance), so that a small fraction of the signaling current may find its way to the calling subscribers line, to satisfy the calling subscriber that a call is being sent.

It will be seen that I have provided a common battery telephone exchange system including telephone lines extending from sub-stations to an exchange, connecting a'pparatus at the exchange for uniting lines in conversation, a common battery adapted'for inclusionin bridges of the telephone lines, said connecting apparatus serving to connect .one terminal of the battery with one limb of each telephone line, the other terminal of said battery being connected with the remaining limb of each telephone line independently of said connecting apparatus, and impedance devices in the battery bridges between which the battery is disposed, the

isc

J1 -nected w1th the remaimn jack switch of the associated line and constitutin a cut-cit relay for such line, the jack swltch and connecting apparatus havmg contacts adapted for engagement to make and break the parallel connection between said relays.

In the claims I speak of the impedance devices connected in parallel or in multiple relation and relays connected in parallel or in multiple relation meaning thereby that these devices or relays have their terminals conductively or metallically' united, so that battery current finds passage from one pair of united terminals to the other pair of united terminals over both devices or relays. In other words, the claims are intended to mean that the impedance devices or relays have common terminals, from one of which to the other of which batter current may flow over both impedance evices or rela s, the battery current'passing from the sai other common terminal on.

While I have herein shown and articof my invention,I do not wish tobe limited thereto, as changes may readily be made without departing from the spirit'thereof, but, having thus described my invention'fI claim as new and desire to secure by Letters Patentthe following 1. A common battery telephone exchange system including telephone lines extending from sub-stations to an exchange, connecting apparatus at the exchange for unitmg lines in conversation, a common battery I adapted for inclusion in bridgesof the telehone-lines, said connecting ap aratus servmg to connect one terminal 0 the battery with one limb of each telephone line, the other terminal of said battery bein ,con-

l1mb '0 each telephone line independen y of said connecting apparatus, and impedancedevices' in the battery bridges between which the battery is disposed,'the portions of the batlimbs of thetelephon'e" lines through the agency of the connecting apparatus 'melud from sub-stations to an exchange, connecting apparatus at the exchange for uniting lines in conversation, a common battery adapted for inclusion in bridges of the telehone lines, said connecting apparatus servmg to connect one terminal of the'battery with one limb of each telephone line, the other terminal of said battery bein' connected' with the remaining llmb 0 each telephone line independentl of said connecting apparatus, and impe' anoe devicesin the battery bridges between which the battery is disposed, the portions of the battery other terminal of said battery bein as impedance, relays that enter intothe exchange'equipment and are in paralleli' -f 2. A common batter telephone exchange 7 system-including telep one lines extending bridges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including as impedance, relays that enter into the exchange eqluipment and are in parallel, one of the re ays being connected with the connecting apparatus and the other of the rela s being connected with a jack switch of t e associated line, the jack switch and connecting apparatus ha'vin contacts adapted for engagement to ma e and break the parallel connection between said relays.

3. A common battery telephone exchange system including telephone lines extending from sub stations to an exchange, connecting apparatus at the exchange for uniting lines in conversation, a common battery adapted for inclusion in bridges of the telephone lines, said connecting ap aratus serv- 1n to connect one terminal 0 the battery with one limb of each telephone line, the

connected with the remaining limb of eac telephone lme independentesly ing apparatus, and imp ance devices in the of said connectbattery bridges between which the battery I is disposed, the portions of the battery the telephone lines through the agency of the connecting apparatus includin as impedance, relays t at are 1n paralle one of the relays in one of the bri ges being connected, with the connecting apparatus and entering into t-he control of a clearing-out signal and the other of the relays being connected with a jack switch of t line and constituting a cut-off relay for such line, the jack switch and connecting apparae tus having contacts adapted for engagement to make and break the parallel connection between said relays.

4. A telephone line, a battery for supplyingthe same with current and in bridge between the sides of the telephone line, connecting apparatus for connecting said tele- -bridges that are connected with the limbs of v e associated phone-line with another telephone line, said connecting apparatus serving to connect one limb-of said telephone line with one end of the bridge conductor containing said bat- 'tery, the other limb of said telephone line being connected with the other end of said bridge conductor independently of the connecting ap ratus, and an im dance device on one s1 e of said battery in said bridge and two impedance devices, in the form of relays, in multiple relation, upon the otherside of said battery in said bridge.

5. A telephone line, a battery or supply ing the same with current and in bridge between thesides of the telephone line, connecting apparatus for connecting said telephone ine with another telephone line, said connecting apparatus serving to connect one limb of said telephone line with one end of the bridge conductor containing said battery, the other limb of said telephone line 1 being connected with the other end of said bridge conductor inde endently of the connecting apparatus, and on one side of said battery in said bridge and two impedance devices, in the form of relays that enter into the exchange equipment and are, in multiple relation, upon the j other side of said battery in said bridge, one 1 of the relays being connected with the connecting apparatus and the other of the relays being connected with a jack switch of the associated line, the jack switch and connecting apparatus havin contacts adapted for engagement, to ma e and break the parallel connection between said relays.

6. A telephone line, a battery for supplying the same with current and in bridge between the sides of the telephone line, connecting apparatus for connecting said telephone line with another telephone line, said connecting apparatus serving to connect one limb of said telephone line with one end of the bridge conductor containing said bat tery, the other limb of said telephone line being connected with the other end of said bridge. conductor independently of the connecting apparatus, and an impedancedevice on one side of said battery in said bridge and two impedance devices, in the form of relays, in multiple relation, upon the other side of said battery in said bridge, one of the relays being connected with the connect- 4 ing apparatus and entering into the control of a clearing-out signal and the other of the relays being connected with a jack switch of the associate line and constituting a cut-01f relay. for such line, the jack switch and connecting apparatus having contacts adapted for engagement, to make and break the parallel connection between said relays.

7. A common battery telephone exchange system including telephone lines extending from sub-stations to an exchange, connecting apparatus for uniting lines in conversatlon, a common battery at the exchange adapted to have one terminal connected with one limb of each of the connected telephone lines by said connecting apparatus, the other terminal of said battery being connected with the remaining limbs of said telephone lines independently of said connecting apparatus, an operators telephone set, a relay having an armature switch, which, when unattracted, serves normally to include the telephone set in bridge of the connecting'apparatus, and circuit connections,

governed by the connecting end of said connecting apparatus, for closing I circuit through said relay to remove the operators telephone set from association with the con necting apparatus, the battery, by having direct connection with only one of the conductors of the connecting apparatus, serving to prevent cross talk that might arise an impedance device j [bridges between which the battery roac es were both terminals of "the battery connected with both talking conductors of the connecting apparatus.

8. A'common battery telephone exchange system including telephone lines extending from sub-stations to an exchange, connec ing apparatus at the exchange for uniting l1nes in conversation, a common battery adapted for inclusion in bridges of the telephone lines, said connecting apparatus serv- -ing to connect one terminal of the battery With one limb of each telephone line, the

other terminal of said battery being connected with the remaining limb of each telephone line independently of said connecting apparatus, and impedance devices" in the battery bridges between which the battery is disposed, the portions of the battery bridges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including imtery bridges between which the battery is disposed, the portions of the battery bridges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including impedance devices that are in parallel, one of said impedance devices constituting a cut-off relay.

10. A common batter'ytelephone exchange system including telephone lines extending y from sub-stations to an exchange, connecting apparatus at the exchange for uniting lines in conversation, a common battery adapted for inclusion in bridges of the telephone lines, said connecting apparatus servingto connect one terminal of the battery with one limb of each telephone line, the other terminal ofsaid battery being connected with the remaining limb of each telephone line,

independently of said connecting apparatus,

and impedance devices in the battery is disposed, the portions of the battery bridges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including impedance devices that are in parallel, one of said im peldance devices constituting a cord signal re ay.

11. A cominon battery telephone exchange system including telephone lines extending its from sub-stations to an exchange, connecting apparatus at the exchange for uniting lines in conversation, a common battery adapted for inclusion in bridges of the telephone lines, said connecting apparatus serving to connect one terminal of the battery with one limb of each telephone line, the other terminal of said battery being connected with the remaining limb of each telephone line independently of said connecting apparatus, and impedance devices in the battery bridges between which the battery is disposed, the portions of the battery bridges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including impedance devices that are in parallel, one of the impedancedevices being connected with the connecting apparatus and the other of the impedance devices being connected with the jack switch of the associated line, the jack switch and connecting apparatus having contacts adapted for engagement to make and break the parallel connection between said impedance devices.

12. A common battery telephone exchange system including telephone ines extending from sub-stations to an exchange, connect ing apparatus at the exchange for uniting of the telephone lines through the agency lines in conversation, a common battery adapted for inclusion in bridges of the telephone lines, said connecting ap aratus serving to connect one terminal 0 the battery with one limb of each telephone line, the other terminal of said batte being connected with the remainin lim of each telephone line independent y of said connecting apparatus, and impedance devices in the battery bridges between which the battery is disposed, the portions of the battery bridges that are connected with the limbs of the connecting apparatus including impedance devices that are in parallel, one of said impedance devices constituting a cutoff relay, one of the impedance devices oeing connected with the connecting apparatus and the other of the impedance devices being connected with the jack switch of the associated line, the jack switch and connecting apparatus having contacts adapted for engagement to make and break the parallel connection between said relays.

13. A common battery telephone exchange system including telephone lines extending from sub-stations to an exchange, connecting apparatus at the exchange for uniting lines in conversation, a common batte adapted for inclusion in bridges of the telephone lines, said connecting apparatus serving to connect one terminal of the battery with one limb of each telephone line, the other terminal of said ,battery being connected with the remainin limb of each telephone line independent y of said connecting apparatus, and impedance devices in the battery bridges between which the batter is disposed, the portions of the battery bri ges that are connected with the limbs of the telephone lines through the agency of the connecting apparatus including impedance devices that are in parallel, one of said impedance devices constituting a cOrd signal relay, one of the impedance devices being connected with the connecting apparatus and the other of the impedance devices being connected with the jack switch of the associated line, the jack switch and connecting apparatus having contacts adapted for engagement to make and break the parallel connection between said relays. I

14. A multiple switch-board system including telephone lines extending from stations to an exchange, line si al devices for said telephone lines, cut-o rela s for excluding said line signal devices rom operative relation with the telephone lines, connecting apparatus for uniting lines in conversation and serving to operate the cut-oil relays to remove the line si a1 devices from association with the telep one lines, apparatus governed by the called line for removing the control of the connectin ap aratus over the cut-off relay of the cal ed line and to restore the controlof said cut-off relay to the called line, and a clearing-out indicator in association with the connecting apparatus and having its association with the calling line governed by the connecting apparatus, the cut-off relay of the calling line being governed by the connecting apparatus exclusively of the calling line, whereby said clearing-out indicator may be 0 erated by the calling line without causing t e line signal of the calling line, to be displayed durin the time that the connecting apparatus is associated with the calling line.

15. A telephone exchange system including telephone lines extendlng from stations to an exchange, connecting apparatus for uniting lines in conversation, a switch for making and breaking a conductor of said connecting apparatus, a relay overnin said switch and energized, when t he calle party responds, to cause said switch to complete the conductor whose continuity is governed by said switch, a source of signaling current adapted for connection w1th the called telephone line on a side of said switch toward the called telephone line, and a connection bridging the gap controlled b said switch between the sections of sai conductor and forming a path which is partially opaque to current from said source, whereby a limited uantity only of calling current is omitted to pass to the calling line, to in icate to the callin arty that the called arty is being signa ed 16. A teliiphone exchan e system including telephone lines extendlng from stations to an exchange, line signal devices for said telephone lines, cut-0E relays for excluding said line signal devices from operative relation with the telephone lines, connecting apparatus for uniting lines in conversation and serving to operate the cut-0E relays to remove the line signal devices from association with the telephone lines, apparatus governed by the called line for removing the control of the connecting apparatus over the cut-off relay of the called line and to re store the control of said cut-oil relayto the called line, and a clearing-out indicator in association with the connecting apparatus and having its association with the calling line governed by the connecting apparatus, the cut-off relay of the calling line being governed by the connecting apparatus exclusively of the calling line, whereby said clearing-out indicator may be operated by the calling line without causing the line signal of the calling line to.be displayed during the time that the connecting apparatus is associated with the calling line.

17. A telephone exchange system including telephone lines extending from stations to an exchange, line signal devices for said telephone lines, connecting apparatus for .umting lmes in conversation, means whereby the signals occasioned by said line signal devices may be efiaced when calls are answered at the exchange, apparatus governed by the called line for removing the control of the connecting apparatus over the line signal of the called line during connection of the called line with the connectin apparatus, and a clearing-out indicator in association with the connect-in apparatus and having its association wit a calling line governed by the connecting apparatus, the means for controlling the line signal of the ipa eaa calling line being governed by the connecting apparatus exclusively of the calling line, whereby-said clearing-out indicator may be operated by the calling line without causing the line signal of the calling line to be displayed during the time that the connecting apparatus is associated with the calling line.

18. A multiple switch-board", system including telephone lines extending from stations to an exchange, line signal devices for said tele hone 'lines, connecting apparatus for uniting lines in conversation, means whereby the signals occasioned by said line signal devices may be eflaced when calls are answered at the exchange, apparatus governed by the called line for removing the control of the connecting apparatus over the line signal of the called line during connection of the called line with the connecting apparatus, and a clearing-out indicator in association with the connecting apparatus and having its association with a calling line governed by the connecting apparatus, the means for controlling the line signal of the calling line being governed by the collecting apparatus exclusively of the calling line, whereby said clearing-out indicator may be operated by the calling line without causing the'line signal of the calling line to be displayed during the time that the connecting apparatus is associated with the calling line.

In witness whereof, ll hereunto subscribe my name this sixteenth day of January HELMER R. CORWIN.

Witnesses G. L. Cause, L. G. STROH. 

